import numpy as np

if __name__ == '__main__':
    a = 1
    b = 2

    c = a / b
    print(c)

    m = np.array([1, 2, 3])

    n = m / 2
    print(n)

    A = np.array(
        [
            [9, -1, -1],
            [-1, 8, 0],
            [-1, 0, 9]
        ]
    )

    # 第一个是行，第二个是列的范围
    print(A[0, 0:])
    print(A[0, 1:])
    print(A[0, 2:])
